lotus/extern/sector-storage/fr32/readers.go
2020-09-07 15:48:41 -04:00

134 lines
2.4 KiB
Go

package fr32
import (
"io"
"math/bits"
"golang.org/x/xerrors"
"github.com/filecoin-project/go-state-types/abi"
)
type unpadReader struct {
src io.Reader
left uint64
work []byte
}
func NewUnpadReader(src io.Reader, sz abi.PaddedPieceSize) (io.Reader, error) {
if err := sz.Validate(); err != nil {
return nil, xerrors.Errorf("bad piece size: %w", err)
}
buf := make([]byte, MTTresh*mtChunkCount(sz))
return &unpadReader{
src: src,
left: uint64(sz),
work: buf,
}, nil
}
func (r *unpadReader) Read(out []byte) (int, error) {
if r.left == 0 {
return 0, io.EOF
}
chunks := len(out) / 127
outTwoPow := 1 << (63 - bits.LeadingZeros64(uint64(chunks*128)))
if err := abi.PaddedPieceSize(outTwoPow).Validate(); err != nil {
return 0, xerrors.Errorf("output must be of valid padded piece size: %w", err)
}
todo := abi.PaddedPieceSize(outTwoPow)
if r.left < uint64(todo) {
todo = abi.PaddedPieceSize(1 << (63 - bits.LeadingZeros64(r.left)))
}
r.left -= uint64(todo)
n, err := r.src.Read(r.work[:todo])
if err != nil && err != io.EOF {
return n, err
}
if n != int(todo) {
return 0, xerrors.Errorf("didn't read enough: %w", err)
}
Unpad(r.work[:todo], out[:todo.Unpadded()])
return int(todo.Unpadded()), err
}
type padWriter struct {
dst io.Writer
stash []byte
work []byte
}
func NewPadWriter(dst io.Writer) io.WriteCloser {
return &padWriter{
dst: dst,
}
}
func (w *padWriter) Write(p []byte) (int, error) {
in := p
if len(p)+len(w.stash) < 127 {
w.stash = append(w.stash, p...)
return len(p), nil
}
if len(w.stash) != 0 {
in = append(w.stash, in...)
}
for {
pieces := subPieces(abi.UnpaddedPieceSize(len(in)))
biggest := pieces[len(pieces)-1]
if abi.PaddedPieceSize(cap(w.work)) < biggest.Padded() {
w.work = make([]byte, 0, biggest.Padded())
}
Pad(in[:int(biggest)], w.work[:int(biggest.Padded())])
n, err := w.dst.Write(w.work[:int(biggest.Padded())])
if err != nil {
return int(abi.PaddedPieceSize(n).Unpadded()), err
}
in = in[biggest:]
if len(in) < 127 {
if cap(w.stash) < len(in) {
w.stash = make([]byte, 0, len(in))
}
w.stash = w.stash[:len(in)]
copy(w.stash, in)
return len(p), nil
}
}
}
func (w *padWriter) Close() error {
if len(w.stash) > 0 {
return xerrors.Errorf("still have %d unprocessed bytes", len(w.stash))
}
// allow gc
w.stash = nil
w.work = nil
w.dst = nil
return nil
}